Limitations of Doppler echocardiography in the assessment of prosthetic valve hemodynamics

The purpose of this study was to determine the relationship between effective orifice areas of mechanical valves in the aortic position assessed by Doppler echocardiography, and published data from in vitro studies. Eighty-six patients with a normally functioning Standard St. Jude Medical (n = 56) or Björk-Shiley (n = 30) prosthesis in the aortic position were studied. Valve sizes varied between 19 and 27 mm. Pressure gradient was calculated by the Bernoulli, and effective orifice area by the continuity equation. Published data on prosthetic orifice areas from in vitro pulsatile flow experiments using the Gorlin formula were used for comparison. A weak correlation was present between Doppler derived pressure gradient and in vitro estimated effective orifice area, which significantly decreased with increasing valve size (R = -0.61; p < 0.0001). There was only a moderate correlation between Doppler derived and in vitro estimated effective orifice areas whether sewing ring diameter or left ventricular outflow tract diameter was used in the Doppler studies (R = 0.75 and R = 0.71, p < 0.0001, respectively). The difference between in vitro measured and Doppler derived areas was greater with Standard St. Jude Medical than with Björk-Shiley valves, both using the sewing ring diameter (1.04 +/- 0.61 cm2 vs. 0.53 +/- 0.39 cm2, p < 0.0003) and the outflow tract diameter (1.20 +/- 0.68 vs. 0.68 +/- 0.46 cm2, p < 0.006). The presence of atrial fibrillation, concomitant mitral valve replacement, small prosthesis size (19 to 23 mm) or a postoperative interval of less than one year did not change the uniform underestimation of prosthetic orifice areas by Doppler echocardiography. These findings are attributable to pressure recovery and localized transprosthetic velocities, and should be taken into account in the case of a suspected prosthesis malfunction.

[Quantitative evaluation of myocardial perfusion with ultrafast magnetic resonance tomography]

With the advent of ultrafast Magnetic Resonance Imaging (MRI), it is now possible to produce images with high temporal resolution. This gives the opportunity to record the passage of the paramagnetic contrast material Gadolinium-DTPA through the tissue of the heart muscle, yielding information on regional myocardial perfusion. We assessed the accuracy of MRI to detect and quantify reductions in coronary flow secondary to stenosis in dogs and patients. Regional blood flow was measured in dogs by left atrial injection of microspheres labeled with different radioactive isotopes. Signal intensity (SI) curves were generated in regions of interest over the myocardium and the cavum of the left ventricle. A newly developed two-compartment model based on the indicator-dilution method was used for interpretation of the SI-curves. In an optimization process the free parameters of the model equation were fitted to the measured SI-curves. The following flow parameters were determined: model parameter Q*, time to peak intensity (T), maximum signal intensity (SImax) and mean transit time (MTT) as calculated from a gamma variate fit. Absolute blood flow values were calculated for the parameters MTT and Q* assuming that the intravascular volume represents 10% of the total myocardial tissue volume. Measurements were performed on a 1.5 T Magnetom SP (Siemens AG, Erlangen) using a Turbo Flash sequence (TR = 6.5 ms, TE = 3 ms, TI = 100 ms, Flip Winkel = 9 degrees). Endsystolic images (voxel size = 1.8, 2.7, 15 mm3) were taken with an 18-cm Helmholtz surface coil in the short-axis view. A Gd-DTPA bolus (0.05 mmol/kg) was injected into the left atrium of 3 anesthetized closed-chest dogs. From the myocardial SI-curves the different parameters of myocardial perfusion were compared with flow assessed by microsphere injection over a wide range of myocardial blood flows (from 0.04 ml/min/g to 7.6 ml/min/g). A third-order polynominal fit showed a good correlation for the parameter Q* and MTT, whereas T and SImax were found to have a poor correlation. The linear regression analysis for a limited range of < 2 ml/min/g showed a superior estimation of myocardial perfusion for the parameter Q* than MTT. Blood flow > 2 ml/min/g was significantly underestimated by the MRT-measurements, but the parameter Q* showed the smallest amount of the divergent changes.(ABSTRACT TRUNCATED AT 400 WORDS)

Doppler flow velocity measurements during coronary angioplasty

In addition to further studies using Doppler catheters to assess blood flow velocity during coronary angioplasty this study intends to evaluate the functional significance of coronary stenoses and to estimate their hemodynamic relevance prior to and after percutaneous transluminal coronary angioplasty (PTCA). Diameters of coronary artery stenoses were quantified by means of the cardiovascular angiographic analysis system (CAAS) both prior to and following successful PTCA in 37 patients. During coronary artery angioplasty a 12 M:Hz 0.018-in. Doppler-tipped guidewire was used to measure prestenotic and poststenotic parameters of coronary artery flow velocity both prior to and following PTCA. The minimal stenosis diameter was raised from 1.01 +/- 0.58 to 1.76 +/- 0.73 mm (P < 0.0001), the percent diameter stenosis decreased from 63 +/- 11 to 35 +/- 6% (P < 0.0001). Prestenotic average (APV) and maximum peak velocity (MPV), peak velocity integral (PVI), average systolic (ASPV) and diastolic (ADPV) peak velocity, systolic (SPVI) and diastolic (DPVI) peak velocity integral, and diastolic/systolic velocity ratio showed--in contrast to further studies--a considerably significant difference (P < 0.05), whereas poststenotic Doppler data (APV, MPV, PVI, ASPV, DSPV, SPVI, DPVI, DSVR) differed highly significantly (P < 0.0001) prior to and following PTCA. Prestenotic and poststenotic measurements of coronary artery flow velocity differed significantly before and after PTCA and offer the potential for estimating both the hemodynamic relevance of coronary artery stenoses and success of PTCA.

Myocardial infarction in an adult resulting from coronary aneurysms previously documented in childhood after an acute episode of Kawasaki's disease

Coronary aneurysms resulting from a previous episode of Kawasaki's disease are considered an important cause of myocardial infarction in children. A case of a 19-year-old man presenting with an acute myocardial infarction associated with coronary aneurysms is described. These coronary lesions were previously evaluated angiographically and echocardiographically at the age of 13 years, 5 months after the acute episode of a Kawasaki's disease.

Adrenal carcinoma with intravenous extension into the tricuspid valvular plane in a patient with patent foramen ovale

We report on an adrenal carcinoma growing via the inferior vena cava into the right atrium and prolapsing into the right ventricle. A patent foramen ovale determined the pathophysiological and clinical appearance. Instead of an expected caval congestion the main features were paroxysmal dyspnoea and cyanosis. The patient was investigated using echocardiography, magnetic resonance tomography and angiography.

Nitrendipine vs. captopril in essential hypertension: effects on circadian blood pressure and left ventricular hypertrophy

Both nitrendipine and captopril have been shown to reverse left ventricular hypertrophy in hypertensive patients. So far, no study allowed a true comparison of these drugs in this regard and with respect to their potential of reducing circadian blood pressure. Therefore, a total of 86 patients with newly diagnosed arterial hypertension and echocardiographic evidence of left ventricular hypertrophy underwent randomized treatment with captopril (n = 43) or nitrendipine (n = 43). Eighteen patients had to be put on a combination therapy of nitrendipine and captopril during the course of the study to control blood pressure effectively. Before and after the 6th and 38th weeks of treatment all patients underwent ambulatory 24-hour blood pressure monitoring, M-mode echo assessment of left ventricular mass and Doppler evaluation of left ventricular filling. The 24-hour blood pressure data were smoothed with a Fourier series and then compared with a normotensive reference profile with respect to blood pressure load and variability. The daytime and nighttime mean and the office blood pressure were also analyzed. Substance-specific profiles of action were obtained by subtracting the smoothed profiles after therapy from the profiles before therapy. After 38 weeks ambulatory blood pressure had decreased from 152 +/- 11/101 +/- 7 to 137 +/- 13/87 +/- 10 mm Hg on nitrendipine and from 147 +/- 11/99 +/- 6 to 134 +/- 13/89 +/- 9 mm Hg on captopril. The substance-specific profiles calculated for captopril and nitrendipine showed a balanced antihypertensive effect throughout the day and the night. The mean percentage decreases in left ventricular muscle mass under nitrendipine was 15% and did not differ significantly from the decrease of 21% under treatment with captopril (p < 0.001). There is no significant association between the reduction in blood pressure and the regression of left ventricular hypertrophy. In patients with disturbances of left ventricular diastolic function the early-to-late diastolic left ventricular flow ratio and the isovolumetric relaxation time were improved independent of the drug used. It is concluded that a long-term therapy with captopril and nitrendipine leads to a comparable degree of circadian blood pressure reduction and regression of hypertensive left ventricular hypertrophy.

A controlled comparison of continuous ranitidine and intermittent famotidine infusions on gastric pH

Continuous infusions of any given H2-blocking drug have uniformly been found to be superior to intermittent infusions of the same H2-blocking drug in sustaining elevations in gastric pH. Comparisons of intermittent and continuous infusions among different H2-blocking drugs have heretofore not been made. Owing to its greater potency and longer half-life, the authors were interested in determining whether intermittent infusions of famotidine might be as effective as continuous infusions of ranitidine in sustaining elevations of gastric pH. The effectiveness of a continuous intravenous infusion of ranitidine (6.25 mg/hr) was compared with the effectiveness of intermittent intravenous infusions of famotidine (20 mg every 12 hours) in sustaining gastric pH above 4.0 in 18 young, healthy adult male subjects using a randomized two-way cross-over design. Gastric pH was continuously monitored for 24 hours. The intermittent famotidine regimen was determined to be as effective as the continuous ranitidine regimen with respect to the following parameters: (1) the percentage of the 24-hour dosing period during which gastric pH exceeded 4.0; (2) the area under the pH > or = 4 versus time curve; and (3) median gastric pH.

PTCA in elderly patients: acute results and long-term follow-up

Acute results and long-term follow-up of percutaneous transluminal coronary angioplasty (PTCA) in 125 patients aged 75 to 90 years (79 men; 46 female; mean age 78 +/- 3 years), with mainly unstable angina (102 patients) are reported. Successful PTCA was achieved in 96 out of 108 patients (89%); occlusions could be reopened in eight out of 17 patients (47%). Thirty-eight procedures were multiple vessel or multiple lesion PTCA, so that the lesion-related success rate of PTCA was higher (91%). Major complications occurred in seven patients (5.6%) including one procedure-related death. In-hospital mortality was 3% and concerned exclusively patients with unstable angina and unsuccessful procedure. At a mean follow-up of 27 +/- 16 months (2 to 82 months) 13 additional patients had died: 10 from cardiovascular causes, three from cancer. In the meantime, three patients underwent non-fatal myocardial infarction and three elective bypass surgery; 26 patients had repeat PTCA. Eighty-seven of the 93 surviving patients with successful primary procedure and reintervention if necessary, were in anginal class I or II; only six were in class III. We conclude that the success rate of PTCA in elderly patients is comparable to that in younger patients, and that a successful procedure leads to continued relief of symptoms.

Nuclear DNA markers of the Australian tetraploid Microseris scapigera and its North American diploid relatives

The allotetraploid lactucean Microseris scapigera of Australia and New Zealand has presumably arisen in western North America by hybridization between an annual and a perennial diploid species followed by polyploidization and long-distance dispersal. A phylogenetic tree of various North American diploids, based on RFLPs in the nuclear DNA, confirmed the division of the genus into a clade containing the diploid annuals and a clade containing the diploid perennials. Four RFLP markers were shared among all accessions of M. scapigera and all the diploid accessions. Twelve markers found in the outgroup (Uropappus lindleyi) were absent in all Microseris. A cladogram of plants from six populations of M. scapigera based on eight RFLP markers shows a progressive specialization of three clades of two populations each. Two populations without any markers differentiating them from the North American diploids form the basic clade. These consist of plants with an apparently derived morphology that are self-compatible (or agamospermic) and thereby differ from most M. scapigera. Few markers in M. scapigera could be attributed to one or the other parental genome. As yet, we have found only one ITS 1 sequence of the nuclear ribosomal cistrons in M. scapigera. This sequence has features of both parental sequences.

[Recurrent myxoma]

In a now 53-year-old woman, who suffered from recurrent syncope and dizziness, a biatrial myxoma originating from the interatrial septum was resected nearly 4 years ago, and the resulting septal defect was closed by a Dacron patch. In the symptomless patient the recurrent myxoma was revealed by echocardiography. The left atrial myxoma was surgically removed without repeat heart catheterization. This case underlines the importance of regular, echocardiographic follow-up examinations in patients in whom a myxoma has been excised. In case of suspicious findings, an additional transesophageal examination or nuclear magnetic resonance imaging should be performed.

Steady-state pharmacokinetics of theophylline in COPD patients treated with dirithromycin

Steady-state theophylline pharmacokinetic parameters were studied in a panel of 14 patients with chronic obstructive pulmonary disease (COPD). Pharmacokinetic parameters were evaluated before, during, and after a 10-day regimen of the macrolide antibiotic, dirithromycin. The addition of dirithromycin (500 mg orally once daily at 7:00 AM) to a sustained-release theophylline dosing regimen (every 12 hours) elicited small changes in the steady-state pharmacokinetics of theophylline, which were not statistically significant. Mean steady-state plasma theophylline trough concentrations (Css,min) were invariant before, during, and after dirithromycin treatment. Mean average steady-state plasma theophylline concentrations (Cav) declined by 7% during dirithromycin treatment (NS), and mean peak plasma concentrations (Css,max) declined by 12% (NS). Theophylline clearance (CL/F) also remained relatively unchanged during dirithromycin treatment exhibiting an increase of only 11% (NS). Dirithromycin treatment does not significantly affect the steady-state pharmacokinetics of theophylline, and its use in COPD patients is not likely to modify treatment outcomes with theophylline.

[Percutaneous transluminal coronary angioplasty in patients with clearly restricted left ventricular pump function]

Among nearly 2000 consecutive PTCA-patients 42 (36 male, six female; mean age 60 +/- 11 years) had ejection fractions < or = 35% (mean 30 +/- 5%). 34 patients suffered from unstable and eight from stable angina. All had previous myocardial infarction and of these 23 had recent myocardial infarction. Four patients had prior coronary bypass surgery and one had undergone aneurysmectomy. 31 of 42 (= 74%) patients had multiple vessel disease (stenoses > 50%). Successful procedure was achieved in 35 of 42 patients (= 83%). The lesion-related success rate of PTCA was 89%, of recanalization 60%. Six procedures were multiple vessel PT-CA. Major complications occurred in two of 42 patients (one myocardial infarction, one emergency bypass operation). The in-hospital mortality was 2.4%. Follow-up angiography was performed in 22 patients and showed restenoses in nine cases. All patients underwent repeat coronary angioplasty, of these one patient had postprocedural myocardial infarction. The ejection fraction had meanwhile significantly improved from 29 +/- 5% to 36 +/- 7%. Clinical follow-up after 18 +/- 14 months (two to 53 months) was available in 39 of 40 patients, who were discharged from hospital without major complications. 29 patients were free of angina or anginal class II, one had a late cardiac transplant. Five patients had died of cardiac and one of noncardiac causes. Thus, PTCA in patients with severely depressed ventricular function shows acceptable acute results, which are comparable to those of routine angioplasty, continued symptomatic improvement can be achieved. However, the late outcome is significantly worse than in patients with normal left ventricular function.

In vivo evidence that theophylline is metabolized principally by CYP1A in rats

The role of various subfamilies of rat hepatic cytochrome P-450 in the oxidation of theophylline was evaluated by comparing theophylline clearance in control rats and those pretreated with relatively selective inducers and inhibitors of the cytochromes P-450. Pretreatment with the CYP1A inducer, beta-naphthoflavone (BNF), increased theophylline clearance 4.5-fold (p < 0.001), and the CYP1A inhibitor, alpha-naphthoflavone, significantly attenuated the BNF effect. Pretreatment with phenobarbital, an inducer of CYP2B/C in rats, had a far more modest effect, increasing theophylline clearance only 1.6-fold (p < 0.005). The phenobarbital-mediated increase in theophylline clearance was attenuated by orphenadrine, a CYP2B/C inhibitor. The CYP2E inducer, isoniazid and the CYP2E inhibitor, diallyl sulfide were virtually without effect, as was the CYP4A inducer, clofibrate, and the CYP4A inhibitor, 10-undecynoic acid. Ajmaline, and inhibitor of CYP2D, was also without any effect on theophylline clearance. While the powerful CYP3A inducer clotrimazole did not increase theophylline clearance, troleandomycin, an inhibitor of CYP3A, did slow theophylline clearance by about 25% (p < 0.002). Together, these findings suggest that CYP1A is principally responsible for the overall oxidation of theophylline in rats, and that CYP2B/C probably also mediates some theophylline oxidation. The involvement of CYP2D, CYP2E, CYP4A, and CYP3A is relatively trivial.

[Digital subtraction angiocardiography: reliability of densitometric determination of left ventricular volume and ejection fraction]

The angiographic assessment of left ventricular volume (LV) and ejection fraction (EF) by means of the area-length method (ALM) is based upon geometric assumptions, which might lead to erroneous results. With the development of digital subtraction angiocardiography in real-time, densitometric procedures of calculating left ventricular parameters can be used on-line. This study examines both reliability and accuracy of a densitometric technique for evaluating LV and EF in comparison to the single-plane ALM. Contrast images of heart casts and left ventricular angiograms of 54 patients suffering from different cardiac diseases were obtained by the image acquisition and processing system Polytron 1000 VR (Siemens AG, Erlangen, FRG). Digital images of both heart casts and patients were evaluated densitometrically and geometrically by two independent observers. In the phantom study the densitometric method exhibited a significantly (p < 0.01) better agreement with the true values than the ALM. The evaluation of left ventricular angiograms in patients comparing densitometry with the ALM demonstrated a relatively high residual deviation (enddiastolic volume Syx = +/- 27 ml, endsystolic volume Syx = +/- 19.4 ml). This is mainly due to systematic, method-related errors of densitometry and the morphometric technique. The intra- and interobserver variability in calculating EF showed a significantly (p < 0.05) smaller residual deviation for densitometry than for ALM; no significant differences were found for the calculation of LV. In conclusion, we demonstrated that the presented densitometric technique offers an objective and simple means of determining LV and EF with comparable reliability and validity to the area-length method.

[Quantitative evaluation of aortic valve insufficiency in magnetic resonance tomography]

Flow-encoded magnetic resonance (MR) sequences allow the quantitative evaluation of blood flow in any plane of the heart and vessels. For the first time, ejection and regurgitation volumes of the left ventricle in the ascending aorta can be measured noninvasively. Thus, the regurgitation fraction as a reliable measure of aortic valve insufficiency can be determined. The quantitative evaluation of aortic valve insufficiency was done by MR in comparison to ultrasound-Doppler and, in some cases, in comparison to heart catheterization. A good correlation of grading aortic valve insufficiency by the new MR-technique in comparison to clinical graduation is shown. The development of a new noninvasive standard for quantification of aortic valve insufficiency seems possible.

[Left ventricular dilatation after myocardial infarct]

The aim of this prospective study was to investigate if left ventricular dilatation is confined to the early months following myocardial infarction, or if it is a progressive process over several years. One hundred patients (pts) who suffered from stable angina or had undergone myocardial infarction, could be examined twice by coronary arteriography including ventriculography in an interval of 52 +/- 14 months. The patients were retrospectively divided into three groups: 41 pts (group A) had coronary heart disease without prior myocardial infarction, in 29 pts (group B) the first examination was performed within (mean 2 +/- 1 mo.) and in 30 pts (group C) beyond 6 months after myocardial infarction (mean 32 +/- 24 mo). The three groups were comparable concerning clinical data, but more pts with former myocardial infarction had multi-vessel disease (34 of 59 vs 16 of 41 pts) and depressed left ventricular function. Left ventricular angiography was performed in RAO view 30 degrees after enddiastolic pressure (LVEDP) was registered. Left ventricular enddiastolic and endsystolic volumes (EDVI and ESVI) were calculated by use of a modified Simpson's rule equation. In group A, EDVI and LVEDP remained constant, whereas ESVI increased slightly but significantly. Pts of group B and C had significantly higher volumes, which increased significantly in both groups over a mean of 52 months. About half the pts suffered from ventricular dilatation independent of progression of underlying coronary sclerosis. Consecutively, left ventricular ejection fraction decreased and LVEDP rose significantly in both groups.(ABSTRACT TRUNCATED AT 250 WORDS)

A new approach for evaluating circadian blood pressure levels and variability from 24 h ambulatory blood pressure profiles

In 24 h blood pressure monitoring the severity of arterial hypertension is generally classified on the basis of the arithmetic mean of the diastolic blood pressure between 6 AM and 10 PM. In the present study Fourier analysis was used for evaluation of circadian blood pressure level and variability. A common reference profile was calculated on the basis of a group of 50 normotensive profiles. This reference profile is characterized by the fact that the sum of the squares of the distances between the individual profiles and the reference profile is a minimum. The individual 24 h profiles of 103 patients with untreated arterial hypertension were also each described by a Fourier series and were then compared with the normotensive reference profile. The comparison was made not only with respect to the absolute pressure over 24 h but also with respect to the circadian fluctuations in blood pressure. Our results show that the Fourier analysis of 24 h blood pressure profiles presented here can be used for more precise evaluation of 24 h blood pressure profiles.

[Ambulatory blood pressure monitoring: significance of blood pressure variability for progression of heart hypertrophy]

It is known that ambulatory blood-pressure monitoring gives a better prediction of target organ damage and prognosis than clinical blood pressure. Many studies have found a closer correlation for ambulatory blood pressure with left ventricular hypertrophy than clinical blood pressure. One question that is discussed controversely is whether the variability of blood pressure is also a determinant of target organ damage independent of the average level. In 52 patients with elevated casual blood pressure a 24-h ambulatory blood-pressure measurement (Space Labs 90202) was performed and left ventricular hypertrophy was evaluated by M-mode echocardiography. The following parameters of blood pressure variability were calculated from the profiles: the standard deviation of the mean value, the variation coefficient and the parameter of variability as proposed by Schächinger et al. Furthermore a Fourier analysis of the blood pressure data was performed to quantify blood pressure variability. We found no statistically significant correlation between blood pressure variability and left ventricular mass. However, systolic and diastolic blood pressure level showed a significant correlation with left ventricular hypertrophy (r = 0.45 and r = 0.49, p < 0.05). Thus, blood pressure variability as calculated from the ambulatory, non-invasive blood pressure monitoring is a poor predictor for secondary damage of the heart.

Percutaneous transluminal coronary angioplasty in patients with severely depressed left ventricular function

Among nearly 2,000 consecutive percutaneous transluminal coronary angioplasty (PTCA) patients, 42 patients (36 male, 6 female; mean age 60 +/- 11 years) with mainly unstable angina had ejection fractions of < or = 35% (mean 30 +/- 5%). All patients had previous myocardial infarctions; 31 (= 74%) had multivessel disease. Successful procedure was achieved in 35 of the 42 (= 83%) patients, 31 of 35 (= 89%) stenoses could be successfully dilated and 9 of 15 (= 60%) occlusions reopened. In-hospital mortality was 2.4%. Follow-up angiography in 22 of the 35 patients who had been successfully treated showed significant improvement of ejection fraction from 29 +/- 5 to 36 +/- 7%. At clinical follow-up 19 +/- 14 months (2-53 months) after the procedure, nearly all surviving patients were in anginal class I or II, 5 had died from cardiac and 1 from noncardiac causes. Thus, PTCA in patients with severely depressed left ventricular function shows acceptable acute results; attenuation of ventricular dysfunction and continued symptomatic improvement can be achieved. However, late outcome is significantly worse than in patients with normal ventricular function.

Risk of endocarditis in transesophageal echocardiography

The risk of endocarditis associated with transesophageal echocardiography was studied in 101 patients. To evaluate possible bacteremia, blood cultures were performed on samples from consecutive patients who did not have clinical or laboratory evidence of infection. The broth blood culture Signal system was used in all patients, and additionally, the lysis-centrifugation technique was performed in a subgroup of 40 patients to further ameliorate recovery of rapidly phagocytosed germs. Comprehensive criteria for differentiation between true bacteremia and possible contamination were provided by means of simultaneous blood sampling from two separate venipuncture sites and skin specimens from the venipuncture area. Oropharyngeal specimens were cultured for evaluation of possible association of oropharyngeal flora with positive blood culture findings. They revealed facultative pathogenic isolates, as well as physiologic residental flora, in 15 patients. All blood isolates that were recovered simultaneously 6 minutes after the procedure were found to be sterile. Correspondingly, clinical follow-up for 2 weeks was uneventful with regard to episodes of infection. These results indicate that the risk of bacteremia associated with transesophageal echocardiography is extremely low. Thus endocarditis prophylaxis is not required for this procedure.